We’re going to start looking at how things relate to each other, which means we’re going to get into statistics.
If you’re interested in delving more into stats, I recommend this book as a good beginning: https://www.amazon.com/Statistics-Unplugged-Sally-Caldwell-ebook/dp/B00B6FKCWY/ref=mt_kindle?_encoding=UTF8&me=
By now you should be familiar with the idea of summaries and simple things like mean (average) and median. When we look at how things relate to each other, we’re looking for evidence of correlation. And the best way to do that is visually.
There are ways of just getting correlations with raw numbers, but those can be misleading. All of which is leading up to the real reason for this extended introduction: the datasaurus